function dx=Plant(t,x,flag,para)
dx=zeros(2,1);
u=para(1);
d=para(2);

m=3.31;kv=8.6;kc=11.5;
f=kv*x(2)+kc*sign(x(2));

dx(1)=x(2);  
dx(2)=(u-f-d)/m; %%d=0
